Flexible neural interfaces with integrated stiffening shank

ABSTRACT

A neural interface includes a first dielectric material having at least one first opening for a first electrical conducting material, a first electrical conducting material in the first opening, and at least one first interconnection trace electrical conducting material connected to the first electrical conducting material. A stiffening shank material is located adjacent the first dielectric material, the first electrical conducting material, and the first interconnection trace electrical conducting material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 61/802,382 filed Mar. 16, 2013entitled “Flexible Neural Interfaces with Integrated Stiffening Shank,”the disclosure of which is hereby incorporated by reference in itsentirety for all purposes.

STATEMENT AS TO RIGHTS TO APPLICATIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

The United States Government has rights in this application pursuant toContract No. DE-AC52-07NA27344 between the United States Department ofEnergy and Lawrence Livermore National Security, LLC for the operationof Lawrence Livermore National Laboratory.

BACKGROUND

1. Field of Endeavor

The present application relates to microelectrode arrays and methods offabricating microelectrode arrays, and particularly to a microelectrodearray and method of fabricating a microelectrode array such as a neuralinterface with an integrated stiffening shank.

2. State of Technology

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Micro-electrode neural interfaces are an essential tool in neuroscience,targeting the neuronal activity of neurons, enabling researchers andclinicians to better explore and understand neurological diseases. Theseinterfaces use implanted neural probes to bypass damaged tissue andstimulate neural activity, thereby regaining lost communication and/orcontrol with the affected parts of the nervous system.

The most common neural probes are thin-film micromachined probesfabricated on silicon substrates using MEMS fabrication techniques.Neuronal stimulation and recording is conducted at discrete sites (metalpads) along the probes. The metal pads are connected, via metal traces,to output leads or to other signal processing circuitry. Silicon is themost widely used substrate for this type of probe because of its uniquephysical/electrical characteristics. The prevalence of silicon in themicroelectronics industry ensures the neural probes can be relativelyeasily and efficiently fabricated in large numbers utilizing common MEMSfabrication techniques. There is, however, concern regarding thesuitability of these silicon-based neural probes for long-term (i.e.chronic) studies as the silicon will corrode over time when implanted ina body. Furthermore, the continuous micro-motion of the brain can inducestrain between the brain tissue and implanted electrode promotingchronic injury and glial scarring at the implant site. Therefore, thereare outstanding questions regarding the long-term safety andfunctionality of these silicon-based neural probes.

Polymer-based neural probes are an attractive alternative. First, theyare flexible, thereby minimizing strain between the brain tissue and theimplanted probe. Second, they are fully biocompatible and thus suitablefor chronic implantation with no loss of functionality or safety.Finally, these polymer-based neural probes can be easily fabricated inlarge numbers using existing microfabrication techniques.

Unfortunately, the inherent flexibility of the polymer-based neuralprobes means the probes also have a low mechanical stiffness causing thedevices to buckle and fold during insertion. To counteract this,separate stiffening shanks are typically fabricated and then attached toindividual neural probes. This procedure is very time-consuming, and inmost cases, where the stiffening shanks are extremely thin (<50 μmthick), also very difficult.

SUMMARY

Features and advantages of the disclosed apparatus, systems, and methodswill become apparent from the following description. Applicant isproviding this description, which includes drawings and examples ofspecific embodiments, to give a broad representation of the apparatus,systems, and methods. Various changes and modifications within thespirit and scope of the application will become apparent to thoseskilled in the art from this description and by practice of theapparatus, systems, and methods. The scope of the apparatus, systems,and methods is not intended to be limited to the particular formsdisclosed and the application covers all modifications, equivalents, andalternatives falling within the spirit and scope of the apparatus,systems, and methods as defined by the claims.

The present application relates to neural interface devices and methodsof fabrication of neural interface devices. The neural interface deviceincludes a first dielectric material having at least one first openingfor a first electrical conducting material; a first electricalconducting material in the first opening; at least one firstinterconnection trace electrical conducting material connected to thefirst electrical conducting material; and a stiffening shank materialadjacent the first dielectric material, the first electrical conductingmaterial, and the first interconnection trace electrical conductingmaterial. In one embodiment the method of fabricating a neural interfaceincludes the steps of depositing a bottom dielectric material on asubstrate; etching openings in the bottom dielectric material for bottomelectrodes; depositing and patterning bottom electrodes; depositing andpatterning a bottom interconnection trace metal; depositing aninterlayer dielectric material; depositing a stiffening shank material;depositing an interlayer dielectric material; patterning a stiffeningshank from the stiffening shank material; depositing an interlayerdielectric material; depositing and patterning a top interconnectiontrace metal; depositing and patterning top electrodes; depositing a topdielectric material; etching openings in the top dielectric material forthe top electrodes and connector openings; and releasing the device fromthe substrate.

The apparatus, systems, and methods are susceptible to modifications andalternative forms. Specific embodiments are shown by way of example. Itis to be understood that the apparatus, systems, and methods are notlimited to the particular forms disclosed. The apparatus, systems, andmethods cover all modifications, equivalents, and alternatives fallingwithin the spirit and scope of the application as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of the specification, illustrate specific embodiments of theapparatus, systems, and methods and, together with the generaldescription given above, and the detailed description of the specificembodiments, serve to explain the principles of the apparatus, systems,and methods.

FIGS. 1A through 1O illustrate embodiments of Applicant's apparatus,system and method.

FIGS. 2A and 2B provide a flow chart illustrating one embodiment of aprocess of fabricating a neural interface.

FIGS. 3A and 3B illustrate one embodiment of a fully-encapsulatedintegrated stiffening shank.

FIGS. 4A and 4B illustrate one embodiment of a partially encapsulatedintegrated stiffening shank.

FIGS. 5A and 5B illustrate another embodiment of a fully-encapsulatedintegrated stiffening shank.

FIGS. 6A and 6B illustrate the fabrication processes independent of theelectrode spatial arrangement.

FIG. 7 illustrates another embodiment of Applicant's apparatus, systemand method.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, to the following detailed description, and toincorporated materials, detailed information about the apparatus,systems, and methods is provided including the description of specificembodiments. The detailed description serves to explain the principlesof the apparatus, systems, and methods. The apparatus, systems, andmethods are susceptible to modifications and alternative forms. Theapplication is not limited to the particular forms disclosed. Theapplication covers all modifications, equivalents, and alternativesfalling within the spirit and scope of the apparatus, systems, andmethods as defined by the claims.

The apparatus, systems, and methods described and claimed herein enablecombining of a polymer-based neural probe with an integrated stiffeningshank. With the apparatus, systems, and methods described and claimedherein polymer-based neural probes are created with a stiffened areasuitable for insertion into tissue but also with a flexible cable tominimize tissue damage. Utilizing existing microfabrication techniques,large numbers of stiffened polymer-based neural probes can be createdeasily and efficiently. The flexible neural interface with integratedstiffening shank described and claimed herein is suitable forimplantation in both humans and animals for either acute or chronicstudies of various neurological disorders and as interfaces betweenneural tissue and prosthetics. (This assumes the materials comprisingthe device have been properly chosen with regards to theirbiocompatibility.) The neural probes described and claimed herein have aflexible, polymer-based cable, which runs the length of the probe andcontains the electrodes and interconnection traces and a stiffeningshank at the tip (where the electrodes are located). The stiffeningshank is built into the device utilizing standard microfabricationtechniques, and requires no post-fabrication attachment. There aredifferent versions of the flexible neural interface with integratedstiffening shank for example a fully-encapsulated stiffening shank and apartially-encapsulated stiffening shank. (The partially-encapsulatedstiffening shank may not be suitable for chronic studies.) These neuralinterfaces can be created with electrodes on the “top,” on the “bottom,”or on both the “top” and “bottom.”

In addition to being an integrated, wafer-level process, anotheradvantage of this process is that the stiffening shank is not limited tosilicon, unlike traditional non-polymer based neural interfaces. Othermaterials, with varying mechanical properties, can also be used, such asother semiconductors, dielectrics (e.g. glass/quartz/silicon-dioxide,sapphire), ceramics (e.g. alumina), metals (e.g. titanium, tungsten),and others (e.g. silicon-carbide, diamond). Ultimately, the mechanicalproperties and the thickness of the material used for the stiffeningshank dictate the stiffness of the neural interface. Further, theprocess is not limited to vapor-deposited (e.g. sputtering,electron-beam/thermal evaporation, atomic layer deposition, chemical,vapor deposition, physical vapor deposition) materials and thicknesses.The encapsulation process allows free-standing films (e.g. metal foils)to be used.

This disclosure describes a fully-integrated fabrication process forflexible neural interfaces with integrated stiffening shanks. Theseneural interfaces are suitable for implantation in both humans andanimals for either acute or chronic studies of various neurologicaldisorders (e.g. Clinical Depression, Parkinson's Disease, Epilepsy) andas interfaces between neural tissue and prosthetics (e.g. RetinalImplants, Auditory implants).

In one embodiment the device disclosed in the present application is amicroelectrode array, such as a neural interface, with an integratedstiffening shank having electrodes on the top or having electrodes onthe bottom or having electrodes both on the top and on the bottom. Inanother embodiment, the present application relates to a microelectrodearray fabrication method and in particular to a microelectrode neuralinterface fabrication method and method of fabricating a microelectrodearray with an integrated, stiffening shank. Other exampleimplementations provide a microelectrode array having an electricalconduit embedded within a simultaneously-polymerized multi-polymerprecursor layer-based, single polymer film, wherein a portion of theconduit is exposed through the single polymer film.

The flexible neural interface with integrated stiffening shank describedhere is suitable for implantation in both humans and animals for eitheracute or chronic studies of various neurological disorders and asinterfaces between neural tissue and prosthetics. The neural probesdescribed here have a flexible, polymer-based cable, which runs thelength of the probe and contains the electrodes and interconnectiontraces and a stiffening shank at the tip (where the electrodes arelocated). The stiffening shank is integrated into the device utilizingstandard microfabrication techniques, and requires no post-fabricationattachment.

Referring now to the drawings and in particular to FIGS. 1A-1O, oneembodiment of Applicant's apparatus, system and method is illustrated.This embodiment of Applicant's apparatus, system and method isdesignated generally by the reference numeral 100 shown in FIG. 1A.

A substrate 10 is shown in FIG. 1A. Silicon can be used as the substratematerial or other material can be used as the substrate materialprovided the material is compatible with the techniques and chemicalsused during the microfabrication. In some cases, a release layer (e.g.,chrome) is deposited on the starting substrate 10 prior to the firststep of the fabrication process to ensure an easy release of the finaldevice.

A bottom polymer 12 is deposited on the substrate 10. This is shown inFIG. 1B wherein the bottom polymer 12 is shown deposited on thesubstrate 10.

An opening 14 is etched in the bottom polymer for the bottom electrodes.This is shown in FIG. 1C wherein the opening 14 for the bottomelectrodes has been etched in the bottom polymer 12.

The bottom electrodes are deposited and patterned. This is shown in FIG.1D wherein the deposition and patterning of the bottom electrodes isillustrated. The material 16 for the bottom electrodes is deposited andpatterned.

Interconnection trace metal 18 is deposited and patterned. This is shownin FIG. 1E wherein the interconnection trace metal 18 of the bottomelectrodes is illustrated.

An interlayer polymer 20 is deposited on the bottom polymer 12. This isshown in FIG. 1F wherein the interlayer polymer 20 is shown deposited onthe bottom polymer 12 and the interconnection trace metal 18.

Stiffening shank material 22 is deposited on the interlayer polymer 20.This is shown in FIG. 1G wherein the stiffening shank material 22 isshown deposited on the interlayer polymer 20.

An interlayer polymer 24 is deposited on the stiffening shank 22. Thisis shown in FIG. 1H wherein the interlayer polymer 24 is shown depositedon the stiffening shank 22.

The stiffening shank material 22 is patterned to produce a patternedstiffening shank 26. This is shown in FIG. 1I wherein the patternedstiffening shank 26 is shown on the interlayer polymer 20.

An interlayer polymer 28 is deposited on the patterned stiffening shank26. This is shown in FIG. 1J wherein the interlayer polymer 28 is showndeposited on the patterned stiffening shank 26 and the interlayerpolymer 20.

Interconnection trace metal 30 is deposited and patterned. This is shownin FIG. 1K wherein the interconnection trace metal 30 of the topelectrodes is illustrated.

Patterned top electrode metal 32 is deposited and patterned. This isshown in FIG. 1L wherein the patterned top electrode metal 32 isillustrated.

A top polymer 34 deposited on the top electrode metal 32. This is shownin FIG. 1M wherein the top polymer 34 is shown deposited on the topelectrode metal 32 and interlayer polymer 28.

Openings 36 are etched in the top polymer for the top electrodes andexternal connections. This is shown in FIG. 1N wherein the openings 36for the top electrodes and external connections have been etched.

The final release of the device is illustrated in FIG. 1O. The substrate10 has been removed as shown in FIG. 1O.

Referring now to FIGS. 2A and 2B, the flow chart illustrates the processof fabricating a neural interface with integrated stiffening shank andelectrodes on both the top and bottom surfaces. FIG. 2A shows the stepsbeginning with the starting silicon substrate 10. Silicon can be used asthe substrate material or other material can be used as the substratematerial provided the material is compatible with the techniques andchemicals used during the microfabrication. In some cases, a releaselayer (e.g. chrome) is deposited on the starting substrate 10 prior tothe first step of the fabrication process to ensure an easy release ofthe final device.

In the next step a bottom polymer 12 is deposited on the substrate 10.

In the next step an opening 14 is etched in the bottom polymer for thebottom electrodes.

In the next step the bottom electrodes are deposited and patterned. Thematerial 16 for the bottom electrodes is deposited and patterned.

In the next step interconnection trace metal 18 is deposited andpatterned.

In the next step an interlayer polymer 20 is deposited on the bottompolymer 12 and the interconnection trace metal 18.

In the next step a stiffening shank material 22 is deposited on theinterlayer polymer 20.

In the next step an interlayer polymer 24 is deposited on the stiffeningshank material 22.

Referring now to FIG. 2B, the additional steps for fabricating a neuralinterface with integrated stiffening shank and electrodes on both thetop and bottom surfaces are shown.

In the next step the stiffening shank material 22 is patterned toproduce a patterned stiffening shank 26.

In the next step an interlayer polymer 28 is deposited on the patternedstiffening shank 26 and interlayer polymer 20.

In the next step interconnection trace metal 30 is deposited andpatterned.

In the next step patterned top electrode metal 32 is deposited andpatterned.

In the next step a top polymer 34 is deposited on the top electrodemetal 32 and interlayer polymer 28.

In the next step openings 36 are etched in the top polymer for the topelectrodes and external connections.

The next step is the final release of the device. The substrate 10 hasbeen removed.

The process described above (FIGS. 1A-1O and FIGS. 2A-2B) creates aneural interface with electrodes on both the top and bottom surfaces. Ifelectrodes are only desired on the top surface, then the appropriatesteps can be eliminated. If electrodes are only desired on the bottomsurface, then the appropriate steps can be eliminated.

The process is also compatible with different locations of the electrodemetal, with respect to the outer polymer layers, by appropriatere-arrangement of steps. As shown in the process described above, thebottom electrodes are flush with the bottom polymer layer and the topelectrodes are underneath the top polymer layer (i.e. effectivelyrecessed from the top polymer layer). In another example implementation,the top electrodes can be on top of the top polymer layer by depositingand patterning them after the openings in the top polymer layer. Inanother example implementation, posts in the substrate material can beetched at the electrode locations prior to the deposition of the bottompolymer layer. This has the effect of recessing the bottom electrodesfrom the bottom polymer surface. In another example implementation, thebottom electrode material can be deposited before the bottom polymerlayer, which has the effect of putting the bottom electrodes on theoutside of the device (i.e. the bottom polymer layer). These differenttop and bottom electrode locations, with respect to the polymer layers,can be mixed and matched with this process to create a variety ofdifferent neural interfaces.

The process described above creates a neural interface with only twolayers of interconnection trace metal (one for the top electrodes andone for the bottom electrodes). This same process can be used withmultiple layers of interconnection trace metal for both the top andbottom electrodes. Each additional interconnection trace metal layerrequires the use of another interlayer polymer layer (with appropriateopenings between the interconnection trace metal layers). Differentnumbers of interconnection trace metal layers can be used for the topand bottom electrodes. One example would be a process/interface in whichthe top electrodes use 3 layers of interconnection trace metal and thebottom electrodes use 4 layers of interconnection trace metal.

The outlined fabrication steps are independent of the neural interfacedimensions (length, width, thickness, overall shape) and the electrodeproperties (number, spatial arrangement, thickness, shape, material).

The fabrication process is independent of the specific type of polymerused to create the neural interface. Polymides and parylenes(poly(p-xylylene) are the two most commonly used polymers due to theirbiocompatibility. Other polymers can be used (provided these materialscan be deposited and etched), although these other polymers may not bebiocompatible and, thus, the neural interfaces created with thesematerials may not be suitable for chronic and/or acute implantationstudies.

The fabrication process is independent of the specific materials usedfor the interconnection trace metals and the electrode metals. Althoughmetals (e.g., gold, titanium, platinum, iridium) are the most common,due to their ease of deposition and patterning, any conductive material(e.g. other metals, conductive polymers, conductive inks) can be used.In addition, although it is shown that separate metal layers are usedfor the electrode metal and interconnection trace metal, thisfabrication process allows a single material to be used for both theelectrode metal and interconnection trace metal by elimination of theelectrode metal deposition and patterning steps. This fabricationprocess does not require each metal layer (interconnection trace metalor electrode metal) to be comprised of the same material. A differentconductive material can be used for each metal layer to meet the desiredelectrical and mechanical specifications.

The fabrication process is also independent of the specific materialused for the stiffening shank. It is also independent of the dimensions(length, width, thickness, overall shape) of the stiffening shank. Anymaterial that can be deposited and etched can be used. For Version 1 ofthe device (Fully-Encapsulated), the final device should bebiocompatible and suitable for chronic and acute implantation studies,regardless of whether the stiffening shank material is biocompatible(provided the chosen polymer is biocompatible). For Version 2 of thedevice (Partially-Encapsulated), unless the stiffening shank material isbiocompatible, the neural interface created may not be biocompatible andtherefore may not be suitable for chronic and/or acute implantationstudies.

Referring now to FIGS. 3A and 3B a fully-encapsulated integratedstiffening shank is illustrated. The fully-encapsulated integratedstiffening shank is designated generally by the reference numeral 300.The material used for the integrated stiffening shank does not need tobe biocompatible, as once the fabrication process is complete, theintegrated stiffening shank is not exposed. Provided the chosen polymerfor the flexible neural interface is biocompatible, the finished deviceshould be biocompatible and suitable for long-term implantation.

FIGS. 3A and 3B are top-down (top) and cross-section (bottom) views ofthe flexible neural interface with a fully-encapsulated integratedstiffening shank. The cross-section view 3B shows the cross section ofthe device 300 through the line and arrows specified in FIG. 3A. Thedevice 300 has a multilayer body 302. The device 300 has an integratedshank 304. The bottom electrodes 306 are flush with the bottom polymerlayers and the top electrodes 308 are recessed from the top polymerslayers. The electrodes are sandwiched between the polymer layers andconnected by traces 310. For simplicity, the connector region of thedevice is not shown. The integrated stiffening shank is only at the tipof the device (at the electrode regions) where the device will beinserted. The integrated stiffening shank does not extend the fulllength of the polymer cable.

Referring now to FIGS. 4A and 4B a partially encapsulated integratedstiffening shank is illustrated. The partially encapsulated integratedstiffening shank is designated generally by the reference numeral 400.To ensure biocompatibility of the final device, and suitability forchronic and/or acute implantation studies, the stiffening shank materialmust be biocompatible because in this implementation the stiffeningshank is not fully encapsulated.

FIGS. 4A and 4B are top-down (top) and cross-section (bottom) views ofthe flexible neural interface with a partially-encapsulated integratedstiffening shank. The cross-section view 4B shows the cross section ofthe device 400 through the line and arrows specified in FIG. 4A. Thedevice 400 has a multilayer body 402. The device 400 has an integratedshank 404. The bottom electrodes 406 are flush with the bottom polymerlayers and the top electrodes 408 are recessed from the top polymerslayers. The electrodes are sandwiched between the polymer layers andconnected by traces 410. For simplicity, the connector region of thedevice is not shown. The integrated stiffening shank is only at the tipof the device (at the electrode regions) where the device will beinserted. The integrated stiffening shank does not extend the fulllength of the polymer cable.

Referring now to FIGS. 5A and 5B a fully-encapsulated integratedstiffening shank is illustrated. The fully-encapsulated integratedstiffening shank is designated generally by the reference numeral 500.The material used for the stiffening shank does not need to bebiocompatible, as once the fabrication process is complete, thestiffening shank is not exposed. Provided the chosen polymer for theflexible neural interface is biocompatible, the finished device willalso be biocompatible and suitable for long-term implantation.

FIGS. 5A and 5B are top-down (top) and cross-section (bottom) views ofthe flexible neural interface with a fully-encapsulated integratedstiffening shank. The cross-section view 5B shows the cross section ofthe device 500 through the line and arrows specified in FIG. 5A. In thisdevice 500, the bottom electrode 506 is outside the polymer layer. Thetop electrode 508 is outside the polymer layers. Although not shown, thesame electrode arrangement can also be made with apartially-encapsulated integrated stiffening shank. The integratedstiffening shank is only at the tip of the device (at the electroderegions) where the device will be inserted. The integrated stiffeningshank does not extend the full length of the polymer cable.

Referring now to FIGS. 6A and 6B the fabrication processes presentedhere is shown independent of the electrode spatial arrangement. This isdesignated generally by the reference numeral 600. The top electrodes604 and the bottom electrodes 606 can be overlaid directly on top ofeach other (6A) or offset from each other (6B). Both layers ofelectrodes (top and bottom) can be arranged independently in a varietyof ways (i.e. straight lines, grouped together), with differentinter-electrode spacings, shapes (i.e. circular, oval, square,rectangular), and sizes. It is possible to create a variety ofdifferently shaped and sized electrodes on a single neural interface.

Referring now to FIG. 7 another embodiment of Applicant's apparatus,system and method are illustrated. The neural interface device isdesignated generally by the reference numeral 700. The neural interfacedevice 700 is a multi-layered device that includes a bottom layer 702 ofdielectric material with an electrical conducting material 704. Theintermediate layer 706 consists of a dielectric material with anelectrical conducting material 708 and an electrode 710. Theintermediate layer 712 consists of a dielectric material with anelectrical conducting material 714 and electrodes 710. The intermediatelayer 716 consists of a dielectric material with an electricalconducting material 718 and electrodes 710. The top layer 720 consistsof a dielectric material with 710.

Although the description above contains many details and specifics,these should not be construed as limiting the scope of the applicationbut as merely providing illustrations of some of the presently preferredembodiments of the apparatus, systems, and methods. Otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document. The features ofthe embodiments described herein may be combined in all possiblecombinations of methods, apparatus, modules, systems, and computerprogram products. Certain features that are described in this patentdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.Moreover, the separation of various system components in the embodimentsdescribed above should not be understood as requiring such separation inall embodiments.

Therefore, it will be appreciated that the scope of the presentapplication fully encompasses other embodiments which may become obviousto those skilled in the art. In the claims, reference to an element inthe singular is not intended to mean “one and only one” unlessexplicitly so stated, but rather “one or more.” All structural andfunctional equivalents to the elements of the above-described preferredembodiment that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Moreover, it is not necessary for adevice to address each and every problem sought to be solved by thepresent apparatus, systems, and methods, for it to be encompassed by thepresent claims. Furthermore, no element or component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the claims. Noclaim element herein is to be construed under the provisions of 35U.S.C. 112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for.”

While the apparatus, systems, and methods may be susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and have been described indetail herein. However, it should be understood that the application isnot intended to be limited to the particular forms disclosed. Rather,the application is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the application asdefined by the following appended claims.

The invention claimed is:
 1. A neural interface device adapted to beinserted into tissue, comprising: a neural interface body, wherein saidneural interface body includes an insertion end and a body portionextending from said insertion end; an upper layer made of a firstdielectric material wherein said first dielectric material isbiocompatible, said upper layer extending over said insertion end andsaid body portion of said neural interface body and having at least onefirst opening for a first electrical conducting material wherein said atleast one first opening is located only in said upper layer extendingover said insertion end; a first electrical conducting material in saidfirst opening that provides an electrode in said upper layer; at leastone first interconnection trace electrical conducting material in saidupper layer connected to said first electrical conducting material,wherein said interconnection trace electrical material is located insaid upper layer extending over said insertion end and said body portionof said neural interface body; a lower layer made of a second dielectricmaterial wherein said second dielectric material is biocompatible,wherein said lower layer extends under said insertion end and said bodyportion of said neural interface body; and a stiffening shank betweensaid upper layer and said lower layer wherein said stiffening shank isadjacent said first dielectric material, said first electricalconducting material, and said first interconnection trace electricalconducting material, wherein said stiffening shank is located only insaid insertion end of said neural interface body; and wherein saidstiffening shank is made of a material that provides the neuralinterface device with sufficient stiffening that the neural interfacedevice is adapted to be inserted into tissue.
 2. The neural interfacedevice of claim 1 wherein said stiffening shank is made of asemiconductor material, a glass material, a quartz material, asilicon-dioxide material, a sapphire material, a ceramic material, atungsten material, a silicon-carbide material, or a diamond materialthat provides said stiffening shank and the neural interface device withsufficient stiffening that the neural interface device is adapted to beinserted into tissue.
 3. The neural interface device of claim 1 whereinsaid lower layer includes a second dielectric material wherein saidsecond dielectric material is biocompatible, said lower layer having atleast one second opening for a second electrical conducting material; asecond electrical conducting material in said second opening thatprovides a second electrode in said lower layer; and at least one secondinterconnection trace electrical conducting material connected to saidsecond electrical conducting material.